FEBRUARY 1935
STATION CIRCULAR 110
Tree Borers and
Their Control
0
I
0
Agricultural Experiment Station
Oregon State Agricultural College
CORVALLIS
Tree Borers and Their Control
By
D0NC. MOTE
BORERS
are of common occurrence in orchards, attacking all varieties
of trees. The present circular deals with borers of orchard trees in
general, except the well known andseriously injurious Western Peach and
Prune Root.borer*.
Figure 1. Typical flat-headed borer larva showing general appearance.
Of the fruit tree borers in general, as considered in this circular, it may
he stated that they attack successfully only injured or devitalized trees.
Or to state it another way, it is only trees that have been injured or devitalized that are attacked by borers; there must be some primary cause
for the poor condition of the trees, borer attack being secondary. (This
statement, however, does not hold true for the Peach and Prune Rootborer.) The primary devitalization of the tree may be due to one of several
causes, winter injury, poor drainage, drouth, sun scald, wrong cultural
practices, injury from cultural tools, or, in young trees, failure to get well
established and vigorously growing the first season. This point of primary
devitalization is a very important one in any consideration of borer injury.
Prevent or remove the primary devitalizing factor or factors and borers
are not a problem. Every practice having for its object the thrift and vigor
of the tree is good borer insurance. In combating borers the first and
most important step is to discover the initial cause of devitalization and
attempt by better cultivation, drainage, the use of fertilizer or otherwise to
restore the impaired vitality.
FLAT-HEADED BOREESt
Description. Most noticeably injurious on young trees. The borer is
found generally just beneath the bark as a slender, white, elongate grub
The Western Peach and Prune Root-borer is treated in a separate circular. if
interested in this circular send a postal card request to the Oregon Agricultural Experiment
Station; it is sent free to Oregon growers.
tChrysoboth mali Horn: order Coleoptera: Family Buprestidae.
Chry.wbothris feinoraia OIly.: order Coleoptera: Family Buprestidae.
2
TREE BORERS AND TIIEJR CONTROL
3
with a broad, flattened head, tunneling out broad, flattened channels. The
bark over the burrows is usually discolored and shrunken, the burrows
filled with frass.
The adult is a small, flattened, brownish-green beetle, known as the
metallic wood borer.
Life history and habits. There are two or more species of flat-headed
borers common on fruit trees. Tue life history and habits vary with the
species and vitality of the tree. Tn general the borer spends nearly a year
in the tree, changing to a beetle early in the spring of the second year.
The adult beetles are present in the orchard all
summer long, from May until September, but
they are most active and the majority of the eggs
are laid during June and July. The beetles deposit their eggs singly on the surface of the bark,
choosing preferably roughened areas or scaley
bark. The southwest side of the tree seems the
favorite spot, due, probably, in part to the warm
sun shining on this area and in part to the tendency to sun-scald here. Leaning trees are particularly subject to attack as are young trees with
but little top to shade the trunk.
The young borers upon hatching tunnel directly into the bark and proceed to feed and burrow out winding galleries, increasing in size as
the larva grows. The older borers frequently
tunnel directly through the heart wood, the ellip-
tical shape of the tunnel indicating the kind of
borer at work. By winter time the borers are
almost grown and remain in their tunnels until
spring. The next spring during April and May
they transform to the beetle stage.
The injury. All ages and varieties of fruit trees are attacked. Probably
young trees are most seriously injured. Occasionally several hundred trees
may be killed their first or second season, particularly where high tempera-
tures and a prolonged drough occur, as in 1922, before the trees are well
established. The borer attacking apple works mostly just under the bark
at or above the surface of the ground. The flat-headed borer works oji
prune, peach, and apricot and tunnels through the wood more, ranging over
a greater portion of the tree, working often at and below the soil surface
and even in the brace roots.
Borers can rapidly deplete and destroy a tree after once they attack it.
Often trees which might easily have overcome the effects of the primary
devitalization which invited the attack of borers are killed out in a very
brief time by the borers.
Control must be in the nature of prevention rather than cure. Repellent
washes are of value and are recommended for use particularly on young
trees.
4
AGRICULTURAL EXPERIMENT STATION CIRCULAR 110
WASH No. 1. (a particularly effective wash)
Rock lime
Salt (rock salt)
Rice boiled (cook to a thin paste)
Casein (powdered)
Naphthalene flakes
bushel
2 quarts
3 pounds
2 pounds
2 pounds
Slake the lime in a vessel of sufficient capacity to permit adding other
ingredients. Dissolve the salt in warm water and add the warm salt water
and warm rice paste to the freshly slaked lime while still fairly hot. Obtain
a fairly granular casein and sift slowly into the cool whitewash while stir.
ring. Finally, sift the naphthalene through a coarse screen to remove the
lumps and add while stirring. Add water to make a whitewash the consistency of paint, if wash is to be applied with brush, if to be applied as
a spray thin a little more and strain carefully while filling the spray tank.
WASH No. 2. Same as No. 1, except substitute crude carbolic acid
for the naphthalene flakes, Use the crude carbolic acid at the rate of pint
to six gallons of tile dilute wash.
WASH No. 3.
8 pounds
Quicklime
Casein
Copper sulfate
Flake naphthalene
Water to form a thick paint.
1
pound
pound
pound
Slake the lime in a fair-sized container. Dissolve the copper sulfate
in a small amount of water (best to dissolve the (lay before needed). Add
this copper sulfate solution to the slaking lime. Add the casein and naphthalene as in wash No. 1.
Preliminary to applying the wash, scrape away the loose surface soil
with an old hoe. The wash may then be applied with a regular white-wash
brush or it may be sprayed on the tree. Where using a sprayer cut down
the pressure to about 25 pounds. Apply the wash from the main crotch
down to the ground, puddling the wash at the soil surface. Fifty gallons of
wash will cover about 20 acres of young trees.
A barrel stave or similar protection on the southwest side of the young
tree is advised. This prevents sun-scald and is therefore a protection
against borers.
THE SHOT-HOLE BORERI-
Description. Trees devitalized, the foliage yellow. Trunk or limbs or
both show holes, "shot holes" through bark and into the sap-wood.
Examination of tunnels during summer reveals presence of small dark-
brown beetles one.eighth inch long, blunt and rounded.
"Salt should be omitted in localities where rabbits are a pest of orchard.
fAnisandrus pyri Peck.: order Coleoptera: Family Scolytidae.
TREE BORERS AND THEIR CONTROL
5
Life history. Beetles pass the winter in their tunnels in the limbs and
trunk of infested tree. Become active in late March, April, and May, leave
the tunnels anti fly to other trees, burrowing into the wood of limbs and
trunk. Eggs are deposited along the sides of the burrows;
cross-tunnels are constructed and additional eggs de-
The grubs hatch in a few days, and commence
to feed on a mold or fungus growing on the waHs of the
wood. These grubs do not tunnel in or feed on the wood.
They are active during May and Tune, transforming to
posited.
beetles in July and August. The beetles remain in the
tunnels until the following spring.
Injury. The injury by the shot-hole borer is (lu to the
construction of tunnels and cross-tunnels in the tree by
the adult beetles. They frequently bore through the heart
wood, and on smaller trees and branches may entirely
girdle the infested part. The grubs feed on a fun gous
growth and do not tunnel. Cherries, prunes, and pears
are most seriously injured, but all common fruit and nut
trees are attacked.
Control. This shot-hole borer never attacks perfectly
healthy trees. There must be some other primary or initial cause for the tree becoming devitalized. The primary
trouble may be winter injury, poor drainage, drouth, rootborers, or any one or more of many troubles to which
trees are subject. The initial trouble gives the tree enough
of a setback to permit the formation of what is termed a
sour sap" condition. These beetles belong to a group
known as ambrosia beetles, because they feed their grubs
Figure 3.
on a fungus which they plant in the tunnels they con- Shot-hole
borer.
struct. It is necessary for this sour sap condition to be
present in order for the fungus to grow. The beetles are attracted to and
attack only devitalized trees which have developed a sour sap condition.
The first step in attempting control is to determinc the initial cause
for the poor condition of the tree and take steps to improve it. If poor
drainage, drain; if lack of cultivation, cultivate, etc.; bitt get the tree in a
thrifty growing condition. Seriously infested trees or limbs should be cut
out and burned.
For slightly infested trees or an occasional infested limb, use the fol-
lowing wash.
Water
Soft soap
Crude carbolic acid
1 gallons
gallon
I
pint
Mix and paint over infested portions during late April or May. About
three applications are advised at weekly intervals. Liquid fish oil soap or
other similar material may take the place of the soft soap. Use the wash
with caution, do not apply in excess; do not paint over uninfested portions
of the trees. The material works down the tunnels, destroying the ambrosia
fungus and preventing its growing as food for the developing grubs.
6
AGRICULTURAL EXPERIMENT STATiON CIRCULAR 110
BRONZE APPLE-TREE WEEVIL OF DEAD-BARK BEETLEC
Description and injury. Attacks devitalized apple and prune trees. Injury more prevalent on neglected trees. Areas of bark the size of a dollar
or larger, shrunken, discolored, and dead. Closer
examination shows small circular area with numerous small holes, which are egg punctures. Cutting
into inner bark reveals irregular burrows arid small
pinkish weevil-like grubs.
Seasonal history. Small, rather slender bronze-
black snout-beetles are present on trees in late
April and May. They feed rather promiscuously
on the foliage and blossoms, later seeking the bark
and gouging out holes for egg laying. Grubs hatch
during late May, feed and tunnel more or less all
summer, pass the winter in the tunnels as niature
grubs, transforming to adult beetles in April.
Control. As with other borers, revitalization of
the tree is the main thing. Dormant clean-up
sprays of lye, lime sulfur, or oil are of value. Cut
Figure 4.
Bronze apple-tree weevil.
out the infested bark and dead wood and paint
over the wounds with a good tree paint such as
bordeaux paste. This must be made the day it is
used, slowly stirring raw linseed oil into a quantity of commercially prepared bordeaux powder until a thick paint is formed. Paint carefully, as
injured bark is very susceptible to infection.
NOTE
In reporting injury from borers, or where in doubt regarding the borer
involved, if you will send specimens with your inquiry to the Oregon
Experiment Station, advice can be given you more intelligently. Send
specimens of wood or bark containing grubs if possible; otherwise specimens of the wood or grubs.
eMagdaiis anescen,s Lee.: order Coleoptera: Family Curculionidae.
OREGON STATE' BOARD OF HIGHER EDUCATION
E. C. Sammons
Lief S. Finseth
B. F. Irvine
Willard L. Marks
Herman Oliver
Cornelia Marvin Pierce
F. E. Callister
Beatrice Walton Sackett
-
Portland
Dallas
Portland
Albany
Canyon City
La Grande
Albant'
Salejn
Jiosebury
Chancellor of Higher Education
C. A. Brand
W. J. Kerr, D.Sc., LL.D
STAFF OF AGRICULTURAL EXPERIMENT STATION
Staff members marked are United States Department of Agriculture
investigators stationed in Oregon
President of the State College
Gea. W. Pcavy, M.S.F
Director
Wm. A. Schoenfeld, B.S.A., M.B.A
-\' ice Director
R. S. Besse, H. S
Division of Agricultural Economics
E. L. Potter, M.S---------ricultural Economist in Charge, Divisiri of Agricultural
Economics
lvV.
I-I, Dreeseir, PhI)
A griciilt sirs 1 Ccc ito n-i s
Agricultural Econonust
bar;,, lila nation; cut
Economist (Farm Management)
Associate Economist (Farm Management)
Associate Economist (Farm Management)
Associate Economist (Farm t,Ianagemeni)
S. Buirier, ii S
Division of Animal Industries
P. lvi. Brandt, AM-----Dairy I lusbanduian ; in Charge, Division of Animal industries
Animal Husbandry
Animal Ilusbandmami
0. M. Nelson, M.S
Assistant Animal ilushandman
W. Rodenwold, BS
Assistant Animal 1111 shandirian
A. W. Oliver, H S
Dairy Husbandry
Dairy Husbandman (Dairy Manufacturing)
Gustav Wilstci-, Ph.D
Associate Dairy Hushandnian
I. R. Jones, Phi)
Fish, Came, and Far Animal Management
Assistant in Charge
R. E. Dimmcls, M.S
Poultry Husbandry
Poultry Hushandnian
A. G. Lunn, B.S
Poultry Husbandman
F. L. Knowlton, u.s
Associate Poultry Husbandman
F. F. Fox, M.S
Veterinary Medicine
Veterinarian
B. T. Sinims, DV.M
Poultry Pathologist
W. T. Johnson, B.S., D.V.M
Associate Veterinarian
J. N. Shaw, B.S., D.V.M
Associate Veterinarian, Burrs,; of Animal Industry5
R. Jay, D.V.M
Assistant Poultry Pathologist
M. Dickinson, D.V.M
Associate Veterinarian5
M. Bolin, DV. H
Junior Veteruiarian5
0. H. Muth, D.V.M
Technician
0. L. Searcy, B.S
Division of Plant Industries
Agrononiist ; in Charge, Division of Plant Jndustries
F. Hyslop, B.S
Factn Crops
D. D. Hill, M.S
Associate Agronomist
H. A. Schoth, M.S.Associate Agronomist; Forage Crops and Disease Investigation
Assistant Agronomist
D. C. Sniith, Ph.D
B. B. Robinson, Ph.D
Assistant Plant Breeder, Fiber Flax Investigations"
Grace Cole Fleischrnami, AD
Assistant Botanist, Division of Seed Investigations5
Horticulture
1--lorticulturist
W. S. Brown, USc
Horticulturist (Vegetable Crops)
A. G. B. Bouquet, MS
Horticulturist (Ilorticultural Products)
E. H. Wiegand, B.S.A
Ilcirticulturist (Pomology)
H. Hartnian. M.S
Horticulturist (Nut Culture)5
C. E. Schuster, M.S
Horticulturist (Plant Propagation)
W. P. Duruz, PhD.
ii. D. Scudder, it S
IT. E. Selby, M.S
G. W. Kuhiman, M.S
-
G. F. Waldo, MS--------------------------Assistant Pomologist (Small Fruit Investigations)5
J. C. Moore, MS
T. Onsdorff, B.S
Assistant Horticulturist (Pomology)
Assistant Horticulturist (Horticultural Products)
STATION STAFF(Contin4ed)
Soil Science
Soil Scientist
W. L. Powers, Ph.D
Soil Scientist (Fertility)
C. V. Ruzek, M.S
Irrigation and Drainage Engineer, Bur. of Agric. Engineering
M. R. Lewis, C.E
Associate Soil Scientist
R. E. Stephenson, Ph.D
E. F. Torgerson, B.S
Assistant Soil Scientist( Soil Survey)
J. S. Jones, M.S.A
R. H. Robinson, M.S
J. R. Haag, Ph.D
D. E. Bullis, M.S
H. B. Hatch, B.S
F. E. Price, B.S
C. Ivan Branton, B.S
G. V. Copson, M.S
J. E. Simmons, M.S
W. B. Bollen, Ph.D
D. B. Charlton, Ph.D
Other Departments
Agricultural Chemistry
Chemist in Charge
Chemist (Insecticides and Fungicides)
Chemist (Animal Nutrition)
Associate Chemist (Horticultural Products)
Assistant Chemist
Agricultural Engineering
Agricultural Engineer
Assistant Agricultural Engineer
Bacteriology
--
Bacteriologist in Charge
Associate Bacteriologist
Associate Bacteriologist
Assistant Bacteriologist
Entomology
D. C. Mote, Ph.D
0. Larson, M.S
G. Thompson, M.S
F G. Hinman., M.S
S. C. Jones, M.S
K. W. Gray, B.S
W. D. Edwards, B.S
Hand M. Wilson, A.M
C. E. Owens, Ph.D
S. M. Zeller, Ph.D
B. F. Dana. M.S
Entomologist in Charge
Entomologist (Stored Products Insects)
Assistant Entomologist
Junior Entomologist (Stored Products Insects)"
Assistant Entomologist
Field Assistant (Entomology)
Field Assistant (Entomology)
Home Economics
Plant Pathology
Home Economist
Plant Pathologist
Plant Pathologist
Pathologist (Curley Top Diseases of Vegetables)"
F. P. McWhorter, Ph.D
Plant Pathologist
F. D. Bailey, M.S
Assciate Pathologist (Enforcement of Insecticide Act)"
P. W. Miller, Ph.D
Associate Pathologist (Nut Disease Investigations)"
G. R. Hoerner, M.S
Agent (Hop Disease Investigations)"
T. Dykstra, M.S
Assistant Plant Pathologist (Potato Diseases)"
Roderick Sprague, Ph.D
Assistant Pathologist (Cereal Diseases)"
H. H. Millsap
Agent (Bulb Diseases)"
Pufilicatiosss and News Service
C. D. Byrne, M.S
Director of Information
E. T. Reed, B.S., A.B
Editor of Publications
D. M. Goode, BA
Associate Editor of Publications
J. C. Burtner, B.S
Associate in News Service
Branch Stations
Supt., Sherman Br. Expt. Sta., Morn; Sr. Agronomist"
D. E. Stephens, B.S
L. Childs, A.B
Superintendent, Hood River Br. Eept. Station, Hood River
Superintendent, Southern Oregon Br. Expt. Station, Talent
F. C. Reimer, M.S
D. E. Richards, B.S----------Superintendent, Livestock Br. Experiment Station, Union
H. K. Dean, B.S
Superintendent, Umatilla Br. Experiment Station, Hermistnn"
Superintendent, Harney Valley Br. Experiment Station, Burns
0. Shattuck, M.S
Superintendent, John Jacob Astor Br. Expt. Sta., Astoria
A. E. Engbretson, B.S
G. A. Mitchell, B.S
Acting Superintendent, Pendleton Field Station, Pendleton;
Assistant Agronomist, Division of Dry Land Agriculture
Arch Work, B.S
Acting Supt. Medford Br. Expt. Sta., Medford; Associate
Irrigation Engineer, Bureau of Agricultural Engineering"
W. W. Aldrich, Ph.D...Assistant Horticulturist, Bureau of Plant Industry, Medford"
G. Brown, A.B., B.S Horticulturist, Hood River Br. Expt. Station, Hood River
Associate Entomologist, Sou. Or. Br. Expt. Sta., Talent
L. G. Geniner, M.S
J. F. Martin, M.S Junior Agronomist, Div. Cereal Crops and Diseases, Pendleton"
H. Oveson, M.S
Assistant to Supt., Sherman Br. Experiment Station, Morn
R. B. Webb, M.S
Jr. Agronomist, Sherman Branch Experiment Station, Morn
R. E. Hutchinson, B.S
Asst. to Supt., Harney Valley Br. Expt. Sea., Burns